Sanofi Pasteur Initiates Phase III Study of Investigational Clostridium difficile Vaccine

Sanofi Pasteur, the vaccines division of Sanofi, announced today the initiation of its Phase III clinical program called Cdiffense to evaluate the safety, immunogenicity and efficacy of an investigational vaccine for the prevention of primary symptomatic Clostridium difficile infection (CDI). Clostridium difficile (C. diff) is a potentially life-threatening, spore-forming bacterium that causes intestinal disease. The risk of C. diff increases with age, antibiotic treatment and time spent in hospitals or nursing homes, where multiple cases can lead to outbreaks. The investigational vaccine is designed to help protect at-risk individuals from C. diff, which is emerging as a leading cause of life-threatening, healthcare-associated infections (HAIs) worldwide. 

C. diff toxins cause gastrointestinal disease that can lead to death in approximately eight to 15 percent of infected people, contributing to the approximately 14,000 C. diff-related fatalities in the U.S. each year. Since 20 to 30 percent of patients experience recurrences of CDI, re-hospitalizations and longer hospital stays remain common. In addition, CDI acute care costs U.S. healthcare systems approximately $4.8 billion annually. The investigational C. diff vaccine is designed to produce an immune response that targets the toxins generated by C. diff bacteria, which can cause inflammation of the gut and lead to diarrhea. It ultimately may help prevent a future infection from occurring.
With the emergence of difficult-to-manage strains of C. diff, CDI has become more frequent, more severe and more difficult to treat in recent years, raising concerns about how to control it and prevent transmission, says John Shiver PhD, senior vice president for research & development at Sanofi Pasteur. Vaccination could be an efficacious, cost-effective and important public-health measure to protect individuals from C. diff.
The Cdiffense Phase III clinical program has just started recruiting volunteers at approximately 100 sites in the U.S. for a randomized, observer-blind, placebo-controlled, multi-center, multi-national trial that will include up to 15,000 adults across 17 countries. Volunteers for the study should be age 50 or older and planning an upcoming hospitalization or who have had at least two hospital stays and have received systemic antibiotics in the past year are also eligible. For more information on the Cdiffense trial, visit
The Food and Drug Administration (FDA) granted fast-track designation to Sanofi Pasteurs investigational C. diff vaccine candidate in 2010. The FDAs fast-track program is designed to facilitate the development and expedite the review of new investigational drugs and vaccines that are intended to treat or prevent serious or life-threatening conditions and demonstrate the potential to address unmet medical needs.